R020932J1, Install Manual

Section I I I

Table 3-4: Deaerator Connections

NOTE The deaerator drain and overflow lines (run independently or tied together) typ- ically contain water at >230 ° F and must be routed to a blowdown tank discharge piping at a point prior to the temperature valve sensor. Most deaerators have a high and low pressure condensate return connection. The high pressure condensate return connection is where all system condensate return and separator trap discharge is introduced. Low pressure returns are typically pumped from a condensate collection tank to the low pressure return connection. The high pressure condensate return connection(s) is located below the water line with a sparger tube installed internally. Introducing the steam and hot condensate below the water line in conjunction with using the sparger tube reduces the velocity and turbulence created at the injection point, while minimizing flash steam losses and noise. In all cases, a check valve must be installed, as close to the DA as possible, in the steam heat and condensate return lines to prevent back-feeding. When installing a sparger tube(s) it must be installed so that the holes are in a horizontal position. Steam is injected into the high pressure side of the tank to maintain the desired operating pressure. A Pressure Regulating Valve (PRV) is used for pressure regulation. Each deaerator is equipped with a safety relief valve to prevent overpressurizing of the tank. This valve is typically rated at 50 psi. The safety relief valve must discharge to atmosphere and in a direction that will not cause harm to personnel or equipment. The discharge piping must not contain any valves or other obstructions that could hinder the release of steam. A back pressure regulator is used to help maintain a steady operating pressure in the DA. This valve is set below the safety valves and will vent during minor periods of over pressurization. NOTE BPR sensing line must be plumbed directly to DA pressure sensing port at the gauge connection on top of the DA tank.

Condensate Returns

&

Sparger Tube

Pressure Regulating Valve Safety Relief Valve

Back Pressure Regulation Valve

3.6 SEMI-CLOSED RECEIVER (SCR) Semi-Closed Receiver (SCR) systems are used only in applications that return a large amount (typi- cally > 50%) of high pressure, high temperature, condensate. The SCR is a pressurized vessel that is main- tained at a pressure that will minimize venting (wasting) of the excess system heat contained in the hot condensate returns. Feedwater outlet line sizing is critical. See Section 2.10. Each SCR system is unique and requires individual attention to ensure proper application, installa- tion and operation. Due to the nature and selected use of SCR systems, the system details are addressed in Supplement I - SCR, pages SI-1 through SI-4.

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